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J Neurosurg Case Lessons
J Neurosurg Case Lessons
J Neurosurg Case Lessons
Journal of Neurosurgery: Case Lessons
2694-1902
American Association of Neurological Surgeons

39250833
10.3171/CASE24287
CASE24287
AnatomyAnatomyEndovascular-NeurosurgeryEndovascular NeurosurgeryVascular-DisordersVascular DisordersCase Lesson
Persistent trigeminal artery aneurysm rupture inducing a carotid-cavernous fistula: its presentation and management. Illustrative case
Silveira Luke A MD 1
Delahmetovic Elnur MS 1
Bounajem Michael MD 2
Thakrar Raj MD 1
Ducis Katrina MD 1
Raymond Scott MD, PhD 3
Liebelt Brandon MD 1
1 Division of Neurosurgery, The University of Vermont Medical Center, Burlington, Vermont
2 Department of Neurosurgery, The University of Utah, Salt Lake City, Utah
3 Department of Interventional Neuroradiology, The University of Vermont Medical Center, Burlington, Vermont
Correspondence Luke A. Silveira: The University of Vermont Medical Center, Burlington, VT. luke.silveira@uvmhealth.org.
INCLUDE WHEN CITING Published September 9, 2024; DOI: 10.3171/CASE24287.

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

09 9 2024
09 9 2024
8 11 CASE2428730 4 2024
26 6 2024
© 2024 the authors
2024
the authors
https://creativecommons.org/licenses/by-nc-nd/4.0/ CC BY-NC-ND 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

BACKGROUND

A carotid-cavernous fistula (CCF) is a well-recognized entity resulting from an abnormal connection between the internal carotid artery (ICA) or external carotid artery and the cavernous sinus. Typical CCF symptomology includes proptosis, chemosis, orbital bruit, headache, facial pain, and cranial nerve (CN) palsies. While CCFs most often occur posttraumatically, they can also occur spontaneously, secondary to cavernous ICA aneurysm rupture. Very rarely, they can occur secondary to the rupture of an anomalous persistent trigeminal artery (PTA) aneurysm.

OBSERVATIONS

Herein, the authors describe the case of a 54-year-old woman who presented with a CN VI palsy and headache due to a CCF secondary to a PTA aneurysm rupture. The CCF was ultimately treated via coil embolization of the aneurysm and the parent PTA vessel.

LESSONS

Though such occurrences are rare, clinicians should be vigilant in assessing for the presence of a PTA in patients with a CCF, as a PTA-associated CCF requires unique treatment considerations. In some cases where the PTA plays a crucial role in the posterior circulation supply, preservation of the parent vessel PTA is crucial. However, in cases in which an adequate posterior circulation collateral supply exists, embolization of the aneurysm and the parent vessel PTA is a reasonable treatment option for fistula closure.

https://thejns.org/doi/10.3171/CASE24287

persistent trigeminal artery
aneurysm
carotid-cavernous fistula
ABBREVIATIONS

AICA = anterior inferior cerebellar artery
BA = basilar artery
CCF = carotid-cavernous fistula
CN = cranial nerve
CT = computed tomography
CTA = computed tomography angiography
DSA = digital subtraction angiography
ECA = external carotid artery
ICA = internal carotid artery
PCA = posterior cerebral artery
PCOM = posterior communicating artery
PTA = persistent trigeminal artery
SCA = superior cerebellar artery
SOV = superior ophthalmic vein.
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pmcCarotid-cavernous fistulas (CCFs) result from an aberrant connection between the internal carotid artery (ICA) or external carotid artery (ECA) and the cavernous sinus. CCFs present with symptoms commensurate with the degree of shunting. Typically, patients develop some constellation of proptosis, chemosis, orbital bruit, headache, facial pain, retro-orbital pressure, and cranial nerve (CN) palsies. Rarely, patients can present with subarachnoid or parenchymal hemorrhage. Ocular symptoms occur secondary to backflow into the orbital veins, which represent major tributaries to the cavernous sinus, namely the superior and inferior ophthalmic veins, as well as the central retinal vein. The oculomotor nerve (CN III), trochlear nerve (CN IV), ophthalmic branch of the trigeminal nerve (CN V1), maxillary branch of the trigeminal nerve (CN V2), and abducens nerve (CN VI) all course through the cavernous sinus.1 Hence, CCFs can present with CN palsies affecting any subset of these CNs, with the abducens nerve sitting closest to the carotid and most susceptible to being impacted.

CCF symptom onset latency, progression, and severity are typically acute in cases of high-flow direct fistulas. Indirect CCFs can have a more insidious onset, and diagnosis is often delayed. When suspected, a CCF can be noninvasively detected on computed tomography angiography (CTA) and magnetic resonance angiography with a relatively high sensitivity.1 Ipsilateral dilatation and increased opacification of the cavernous sinus and the corresponding superior ophthalmic vein (SOV) are hallmark radiographic findings suggestive of a CCF, as demonstrated in the present case. Formal digital subtraction angiography (DSA) is the diagnostic gold standard for CCFs, and endovascular therapy is most often the preferred treatment modality via either transvenous or transarterial embolization. The presence of a high-flow direct fistula represents an indication for treatment, and delay in treatment can result in irreversible vision loss. For low-flow indirect fistulas, progression or intolerability of presenting symptoms represents an indication to treat. Those with mild and nonprogressive symptoms, however, can elect watchful waiting, with spontaneous closure of the fistula to be expected in 20%–60% of cases.1

A spontaneous CCF secondary to a ruptured persistent trigeminal artery (PTA) aneurysm is a rare clinical entity, befitting unique endovascular treatment approaches and anatomical considerations. Herein, we describe the case of a healthy 54-year-old woman who presented with a CN VI palsy and headache secondary to a CCF, with a culprit PTA aneurysm rupture identified and ultimately treated endovascularly.

Illustrative Case

A 54-year-old healthy woman presented to the emergency department for evaluation of acute-onset blurred vision, left-sided headache, facial pain, tinnitus, and perceived eye pressure that had started 2 days prior without a known inciting event. Her physical examination was remarkable for a left lateral rectus palsy without associated proptosis or chemosis. No ocular bruit was observed. She underwent head computed tomography (CT), which was unremarkable, and CTA of the head and neck. CTA (Fig. 1) demonstrated asymmetric opacification of the left cavernous sinus, asymmetric dilatation of the left SOV, and a PTA originating from the left cavernous carotid and connecting to the mid–basilar artery (BA) between the anterior inferior cerebellar artery (AICA) and superior cerebellar artery (SCA) origins. A robust left posterior communicating artery (PCOM) was present. DSA confirmed a left PTA as well as a CCF with early opacification of the left cavernous sinus, SOV, pterygoid plexus, and paravertebral plexus. FIG. 1. Axial CTA (A) demonstrates abnormal opacification of the left cavernous sinus (orange arrow) with an anomalous vessel (blue arrowhead) coursing from the left cavernous ICA to the BA. An asymmetrically opacified and dilated left SOV is denoted with orange arrows in the axial (B) and sagittal (C) planes.

The patient underwent transvenous embolization of the identified CCF with a venous approach from the right inferior petrosal sinus across the intercavernous sinus into the left cavernous sinus. Following transvenous coil embolization of the left cavernous sinus, a left ICA injection DSA demonstrated a residual fistula with rapid opacification of the cavernous sinus, pterygoid plexus, and paravertebral veins (Fig. 2). After transvenous embolization, the patient had a persistent headache, facial pain, diplopia, and tinnitus. FIG. 2. Left ICA injection DSA, lateral (A) and anteroposterior (B) views, after transvenous embolization shows persistent shunting with early filling of the cavernous sinus, pterygoid plexus (green arrows), SOV (red arrow), and basilar plexus (blue arrow).

Given the persistence of the direct fistula, the patient was taken for a repeat embolization procedure, this time using a transarterial approach. Selective catheterization of the left PTA was performed. Multiple superselective angiograms from the mid and proximal PTA and the cavernous carotid artery were used to determine the exact point of shunting. The presence of a 2- to 3-mm ruptured aneurysm arising from the proximal PTA was confirmed and targeted as the site for embolization. This small, ruptured aneurysm, though not clearly seen on prior angiograms, was the presumed culprit connection giving rise to the patient’s presenting CCF. Coils were deployed into the identified aneurysm and proximal PTA, resulting in PTA vessel sacrifice and fistula closure (Fig. 3). FIG. 3. Left ICA injection DSA, anteroposterior view (A), demonstrating the PTA (arrow) emanating from the cavernous ICA to the BA. Selective catheterization of the PTA (B). Sagittal (C) and coronal (D) maximum intensity reformats from a cone-beam rotational angiogram obtained at the time of embolization, showing a 2.6-mm aneurysm (asterisks) arising from the proximal PTA and projecting into the posterior cavernous sinus with mixed opacification of the adjacent sinus.

The patient did well postembolization, with no new neurological deficits. Her tinnitus resolved upon waking, and her facial pain decreased more gradually with a course of steroids and gabapentin. Her left CN VI palsy persisted for several weeks postembolization, necessitating the use of a left eye patch to prevent diplopia-associated headaches. However, by her 1-month follow-up after final embolization, her CN palsy had nearly resolved, and she no longer regularly required an eye patch. A repeat 1-month angiogram confirmed no recurrence of the fistula.

Patient Informed Consent

The necessary patient informed consent was obtained in this study.

Discussion

Observations

CCFs predominantly occur unilaterally but can occur bilaterally in 1%–2% of posttraumatic cases. CCFs can be characterized in several ways, including hemodynamic flow, with low-flow indirect fistulas behaving less aggressively than high-flow direct fistulas. They can also be characterized based on their etiology, with approximately 70% resulting posttraumatically and the remainder resulting spontaneously.1 A commonly adopted classification system, the Barrow classification separates CCFs into four categories based on their radiographically demonstrated arterial supply, types A–D. Type A is a high-flow direct fistula from the carotid to the cavernous sinus, whereas types B–D are indirect fistulas distinguished by the source of arterial supply. Type B is supplied by meningeal branches from the ICA, type C by meningeal branches of the ECA, and type D by both ECA and ICA meningeal branches.2

The described patient presented with an acute-onset left-sided abducens nerve palsy accompanied by headache, ipsilateral facial pain, and retro-orbital pressure. CTA supported the diagnosis of a CCF as well as a PTA. DSA confirmed the diagnosis of a direct, Barrow type A CCF. A small PTA-associated aneurysm was suspected on the first diagnostic angiogram; however, it was not clearly seen until a superselective injection of the PTA was performed during the transarterial embolization procedure, illustrating the importance of performing superselective injections on angiograms incorporating anomalous vessels such as a PTA.

The PTA is the most common of the persistent fetal anastomoses between the carotid and vertebrobasilar circulations, incidentally noted on 0.1%–0.6% of cerebral angiograms.3 The PTA represents 85% of persistent adult embryonic anastomoses between the fetal carotid and vertebrobasilar systems. The remaining three described anastomoses are the otic, hypoglossal, and proatlantal intersegmental arteries. These entities collectively represent just 15% of persistent fetal carotid-vertebrobasilar anastomoses identified in adults.3–5 Although rare, PTA aneurysms have been reported in the literature, with approximately 20 such cases of PTA aneurysm rupture resulting in a CCF currently published.6 Available studies estimate that as many as 14%–32% of PTAs are associated with cerebral aneurysms, with this large percentage attributed to dysplasia of the PTA vessel wall or increased hemodynamic stress on the PTA compared to other vessel configurations.4 When ruptured, PTA aneurysms can manifest with direct CCFs, as in our case. Large or giant unruptured PTA aneurysms can present with CN palsies or trigeminal neuralgia.4

Because of their deep location, PTA-associated vascular lesions are not particularly conducive to open surgical treatment. En­dovascular treatment options offer a more practical treatment strategy. A thorough understanding of the anatomical variation in the PTA course and function is essential for guiding choices about treatment options for PTA aneurysms and other vascular pathologies that can be associated with a PTA. These additional pathologies include arteriovenous malformations, moyamoya disease, and vessel occlusion. The PTA can be implicated as the parent vessel giving rise to an intracranial aneurysm, as in our case, or it can function as a conduit for posterior circulation access in treating posterior circulation vascular malformations or aneurysms. Furthermore, understanding the PTA’s contribution to an individual’s posterior circulation may allow otherwise impermissible treatment strategies, such as distal BA vessel sacrifice.4

The PTA most often arises from the posterior cavernous segment of the ICA and connects to the BA between the SCA and AICA.3 Three major variants of the PTA have been classified by Saltzman, with significant treatment implications according to type. In the Saltzman type I anatomy, the BA proximal to the PTA junction is usually hypoplastic or absent, and the PCOM is usually likewise absent or hypoplastic. In this scenario, the PTA supplies the distal BA and both posterior cerebral arteries (PCAs) and SCAs. In the Saltzman type II anatomy, the PTA joins the BA proximal to the SCA. However, the proximal BA is well formed and the PCOMs are present. In this scenario, the PTA is more of an ancillary tributary to the posterior circulation, with the BA and PCOMs functionally supplying the PCAs. In the type III Saltzman anatomy, the PTA terminates as a cerebellar artery. Subtypes IIIa, b, and c refer to the PTA terminating as the SCA, AICA, and posterior inferior cerebellar artery, respectively.3, 7

Our patient’s PTA was consistent with the Saltzman type II anatomy. Angiography demonstrated the presence of robust PCOMs along with a well-formed proximal BA demonstrated on vertebral artery injections. Transvenous embolization was trialed first in this case but was insufficient to occlude the high-flow fistula. Recognition of the Saltzman type II configuration provided the basis for the ultimate, safe transarterial treatment of the fistula via embolization of the PTA aneurysm and the proximal portion of the parent vessel PTA without posterior circulation infarcts that would have arisen if the anatomy were Saltzman type I.

Lessons

A CCF represents an aberrant connection between the carotid artery and cavernous sinus, with low-flow indirect fistulas behaving less aggressively than high-flow direct fistulas. Though such cases are rare, clinicians should be vigilant in assessing for the presence of a PTA in a patient with a CCF, as a PTA-associated CCF requires unique treatment considerations. Identification and satisfactory visualization of a PTA aneurysm may require superselective vessel injections during a cerebral angiogram, given the vessel’s generally smaller caliber and proximity to the tortuous cavernous carotid. For a Saltzman type I PTA aneurysm rupture, preservation of the parent vessel PTA is of the utmost importance to avoid posterior circulation infarction. For Saltzman type II PTA aneurysms with adequate posterior circulation collateral supply, embolization of the aneurysm and parent vessel PTA is a reasonable treatment option for fistula closure.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: Silveira, Ducis, Raymond, Liebelt. Acquisition of data: Silveira, Delahmetovic, Ducis, Raymond, Liebelt. Analysis and interpretation of data: Silveira, Delahmetovic, Ducis, Raymond. Drafting the article: Silveira, Delahmetovic. Critically revising the article: Silveira, Bounajem, Thakrar, Ducis, Raymond, Liebelt. Reviewed submitted version of manuscript: Silveira, Bounajem, Thakrar, Ducis, Raymond, Liebelt. Approved the final version of the manuscript on behalf of all authors: Silveira. Statistical analysis: Delahmetovic. Study supervision: Thakrar, Liebelt.

Correspondence

Luke A. Silveira: The University of Vermont Medical Center, Burlington, VT. luke.silveira@uvmhealth.org.
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References

1. Ellis JA Goldstein H Connolly ES Meyers PM . Carotid-cavernous fistulas. Neurosurg Focus. 2012;32 (5 ):E9.
2. Barrow DL Spector RH Braun IF Landman JA Tindall SC Tindall GT . Classification and treatment of spontaneous carotid-cavernous sinus fistulas. J Neurosurg. 1985;62 (2 ):248-256.3968564
3. Meckel S Spittau B McAuliffe W . The persistent trigeminal artery: development, imaging anatomy, variants, and associated vascular pathologies. Neuroradiology. 2013;55 (1 ):5-16.22170080
4. Wang Y Yu J . Clinical importance of the persistent primitive trigeminal artery in vascular lesions and its role in endovascular treatment. Front Neurol. 2022;13 :928608.35899260
5. O’uchi E O’uchi T . Persistent primitive trigeminal arteries (PTA) and its variant (PTAV): analysis of 103 cases detected in 16,415 cases of MRA over 3 years. Neuroradiology. 2010;52 (12 ):1111-1119.20309534
6. Zenteno M Lee A Moscote-Salazar LR . Rupture of persistent primitive trigeminal artery-basilar artery aneurysm managed with stent-assisted coiling. Asian J Neurosurg. 2018;13 (3 ):817-821.30283555
7. Memis A Demirpolat G Biceroglu S . Persistent trigeminal artery aneurysm: treatment with coil embolization. J Vasc Interv Radiol. 2007;18 (3 ):459-461.17377201
